Semi-physical simulation modeling method and system for low-voltage transformer area

Abstract

The invention belongs to the technical field of power system fault detection and simulation, and particularly relates to a low-voltage transformer area semi-physical simulation modeling method and system.The method comprises the steps that a large amount of real fault data is obtained from an actual low-voltage transformer area and divided into different types of data sets (such as current faults, current magnitude and leakage current), and the data sets are divided into different types of data sets; and various electrical faults can be accurately simulated. According to the method, simulation close to the actual fault condition can be provided for operation and maintenance personnel, and it is ensured that fault simulation is more accurate and comprehensive. Therefore, operation and maintenance personnel can better predict and deal with actual faults when troubleshooting is carried out, and the repair time is shortened. Through semi-physical simulation, different types of faults can be simulated in advance, and a corresponding debugging means is adopted for each fault. Particularly, through the control of the thyristor, the contactor and the leakage current generator, the current fault, the current size problem and the leakage current condition can be simulated.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system fault detection and simulation, and particularly relates to a low-voltage substation semi-physical simulation modeling method and system. Background Art

[0002] Low-voltage substations play a crucial role in the power system. They are not only related to the power consumption quality of power users, but also directly affect the stability and safety of the entire power system. Due to the large number of users connected to low-voltage substations, the load conditions are complex and changeable, and the operating environment is relatively complex, often facing various sudden faults. These faults usually have strong complexity, suddenness, and uncertainty, thus posing high requirements for fault troubleshooting and repair work.

[0003] Specifically, the common fault types in low-voltage substations include: Leakage current fault: Due to the aging of power equipment, insulation damage, or external environmental influences (such as humidity, corrosion, etc.), leakage current can pose safety hazards to power equipment and the power system. The monitoring and positioning of leakage current are difficult, especially in the case of large-scale user concentration or large load fluctuations.

[0004] Over- and under-voltage fault: Due to the instability of power supply, the voltage may be too high or too low. This type of fault usually causes damage or unstable operation of user equipment, and may even lead to the failure shutdown of equipment. Therefore, timely identification and handling of over- and under-voltage faults are crucial for ensuring the safe operation of electrical equipment.

[0005] Open-phase fault: The power supply network of low-voltage substations often includes three-phase power sources. If one of the phases is disconnected or fails, the power equipment cannot operate normally. Open-phase faults often cause damage to equipment such as motors and may affect the power supply quality of the entire low-voltage substation.

[0006] Short-circuit fault: Due to external factors or equipment aging, etc., short-circuit faults often cause problems such as excessive instantaneous current, equipment burnout, and system tripping in low-voltage substations. Short-circuit faults have strong suddenness. Once they occur, they must be identified and protective measures taken as soon as possible to avoid further losses.

[0007] Power theft: Power theft is a common illegal act in low-voltage substations. Power theft not only causes economic losses, but may also lead to equipment failures or even safety accidents such as fires due to unauthorized wiring and illegal circuit modifications. Traditional power theft detection methods may have delays and missed detections. Therefore, real-time monitoring and intelligent detection are particularly important.

[0008] Three-phase current imbalance: Three-phase current imbalance can lead to a reduction in the operating efficiency of equipment and even cause damage to the equipment. By detecting and adjusting the three-phase current imbalance, the operating life of electrical equipment and the system stability can be significantly improved.

[0009] Harmonic pollution: The main sources of harmonic pollution in the power system come from nonlinear loads, such as frequency converters, rectification equipment, etc. The existence of harmonics will not only affect the normal operation of electrical equipment but also may cause problems such as system overheating and electromagnetic interference.

[0010] In view of the simulation and monitoring of these complex faults, it is particularly important to develop an integrated comprehensive fault simulation device. Summary of the Invention

[0011] The purpose of the present invention is to overcome the above-mentioned deficiencies that are not convenient for troubleshooting and repair, and to provide a low-voltage substation semi-physical simulation modeling method and system.

[0012] To achieve the above purpose, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a low-voltage substation semi-physical simulation modeling method, including the following steps: Obtain all the fault data of the low-voltage substation to generate a fault data set; Classify all the fault data into a current fault data set, a current magnitude data set, and a leakage current data set; Select thyristors that meet the current requirements according to the current fault data set; Select contactors that meet the current requirements according to the current magnitude data set; Select leakage current generators that meet the current requirements according to the leakage current data set; Connect the thyristors, contactors, and leakage current generators in parallel to a controller; wherein, the controller is used to control the magnitude and duration of the fault current simulated by the thyristors, to control the on / off of the current-carrying state simulated by the contactors, and to control the current generator to simulate three-phase leakage current or single-phase leakage current.

[0013] A further improvement of the present invention lies in that the specific method for obtaining all the fault data of the low-voltage substation to generate a fault data set is as follows: All the fault data of the low-voltage substation includes fault data in a time series where each fault data includes data points of the current at time 、voltage and leakage current ; For the current 、voltage and leakage current Impart noise with random fluctuations to obtain the true value of the current , the true value of the voltage and the true value of the leakage current :

[0014]

[0015]

[0016] Among them, is the current noise, is the voltage noise, is the leakage current noise; According to the true value of the current , the true value of the voltage and the true value of the leakage current , establish a fault data set based on the time series to obtain:

[0017] Among them, is the total amount of fault data.

[0018] A further improvement of the present invention lies in classifying all fault data into a current fault data set, a current magnitude data set, and a leakage current data set. The specific methods are as follows: The current fault data set is:

[0019] Among them, is the current fault data set, is the fault threshold of the current, is the fault threshold of the leakage current; The current magnitude data set is:

[0020] Among them, is the current magnitude data set, is the minimum value of the normal current, is the maximum value of the normal current, is the minimum value of the normal voltage, is the maximum value of the normal voltage; The leakage current data set is:

[0021] Among them, is the leakage current data set, is the threshold of the leakage current.

[0022] A further improvement of the present invention is that when selecting thyristors that meet the current requirements according to the current fault data set, the thyristors can withstand the maximum fault current is:

[0023] The conduction current of the thyristor after receiving the control signal is:

[0024] wherein, is the response curve of the thyristor, is the control signal of the thyristor, is the corresponding current value in the current fault data set.

[0025] A further improvement of the present invention is that when selecting contactors that meet the current requirements according to the current magnitude data set, the output current of the contactor after receiving the control signal is is:

[0026] The current fluctuation range of the contactor is:

[0027] wherein, is the response function of the contactor, is the current value of the current magnitude data set.

[0028] A further improvement of the present invention is that when selecting leakage current generators that meet the current requirements according to the leakage current data set, the output current of the leakage current generator after receiving the control signal is is:

[0029] The rated current of the leakage current generator is greater than or equal to the maximum leakage current in the leakage current data set:

[0030] wherein, is the function for dynamically adjusting the control signal of the leakage current generator according to the simulated leakage current magnitude, is the current value of the leakage current data set.

[0031] In a second aspect, the present invention provides a low-voltage substation semi-physical simulation model, including: A fault simulation controller, configured to receive a control instruction, parse the control instruction, and generate a thyristor control signal, a contactor control signal, and a leakage current transmitter control signal; A thyristor control module, which is used to receive a thyristor control signal and simulate the magnitude and duration of a fault current according to the thyristor control signal; A contactor control module, which is used to receive a contactor control signal and simulate the on / off operation of the contactor with current according to the contactor control signal; A current transmitter, which is used to receive a leakage current transmitter control signal and simulate three-phase leakage current or single-phase leakage current according to the leakage current transmitter control signal.

[0032] A further improvement of the present invention is that it includes a wiring terminal, which is used to connect to an external system, receive data from the external system, and generate a control instruction to be sent to the fault simulation controller.

[0033] A further improvement of the present invention is that the adjustment range of the current transmitter is 0 - 2.5A.

[0034] A further improvement of the present invention is that the fault current gears of the thyristor control module are 500A, 400A, 300A, 200A, and 100A.

[0035] Compared with the prior art, the present invention has the following beneficial effects: The present invention can accurately simulate various electrical faults by obtaining a large amount of real fault data from an actual low-voltage substation area and classifying it into different types of data sets (such as current faults, current magnitudes, and leakage currents). This method can provide simulations for operation and maintenance personnel that are close to actual fault situations, ensuring more accurate and comprehensive simulation of faults. Therefore, when faced with fault troubleshooting, operation and maintenance personnel can better predict and respond to actual faults, shortening the repair time. Through hardware-in-the-loop simulation, the present invention can simulate different types of faults in advance and take corresponding debugging measures for each fault. In particular, through the control of thyristors, contactors, and leakage current generators, the present invention can simulate current faults, current magnitude problems, and leakage current situations. In this way, when operation and maintenance personnel face similar actual problems, they already have sufficient simulation experience and coping strategies, thereby improving the efficiency of fault diagnosis. Through simulation testing, the present invention can identify potential fault types and fault occurrence conditions in advance, and then optimize equipment selection and operation strategies. Operation and maintenance personnel have fully understood the possible faults through the simulation system and can more quickly locate and repair faults in the actual system, thus significantly reducing the repair time. When conducting simulation testing, the present invention can simulate different types of electrical faults (such as short circuits, overcurrents, leakage currents, etc.), which may cause equipment damage or system instability during actual operation. By discovering potential fault modes in advance, the system design and equipment configuration can be optimized, improving the fault tolerance of the entire system and making it more capable of dealing with complex and sudden fault situations. In summary, the present invention can not only improve the accuracy and efficiency of fault troubleshooting, but also enhance the reliability of the system, reduce operation and maintenance costs, and improve the overall operation and maintenance efficiency through means such as pre-simulation, precise equipment selection, online monitoring, and real-time response. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flowchart of Embodiment 1; Figure 2 is a system diagram of Embodiment 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To further understand the content of the present invention, the following describes the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention and not for limiting it.

[0038] Embodiment 1: Refer to Figure 1 , a hardware-in-the-loop simulation modeling method for a low-voltage substation area, including the following steps: S1. Obtain all fault data of the low-voltage substation area and generate a fault data set.

[0039] S2. Classify all fault data into a current fault data set, a current magnitude data set, and a leakage current data set.

[0040] S3. Select thyristors that meet the current requirements according to the current fault data set.

[0041] S4. Select contactors that meet the current requirements according to the current magnitude data set.

[0042] S5. Select leakage current generators that meet the current requirements according to the leakage current data set.

[0043] S6. Connect the selected thyristors, contactors, and leakage current generators that meet the current requirements in parallel to the fault simulation controller to establish a low-voltage substation semi-physical simulation model. Among them, the fault simulation controller is used to control the magnitude and duration of the fault current simulated by the thyristor, to control the on / off with current simulated by the contactor, and to control the three-phase or single-phase leakage current simulated by the current generator.

[0044] Embodiment 2: See Figure 2 , a low-voltage substation semi-physical simulation model, including: A fault simulation controller, which is used to receive control instructions, parse the control instructions, and generate thyristor control signals, contactor control signals, and leakage current transmitter control signals; A thyristor control module, which is used to receive thyristor control signals and simulate the magnitude and duration of the fault current according to the thyristor control signals; A contactor control module, which is used to receive contactor control signals and simulate the on / off with current of the contactor according to the contactor control signals; A current transmitter, which is used to receive leakage current transmitter control signals and simulate three-phase or single-phase leakage current according to the leakage current transmitter control signals.

[0045] Preferably, it further includes a wiring terminal, which is used to connect to an external system, receive data from the external system, and generate control instructions to be sent to the fault simulation controller.

[0046] Preferably, the adjustment range of the current transmitter is 0~2.5A.

[0047] Embodiment 3: Based on Embodiment 1, this embodiment further defines the specific method for obtaining all the fault data of the low-voltage substation and generating the fault data set.

[0048] Obtain fault data from multiple sensors in the low-voltage substation. These fault data include the current, voltage, and leakage current at each time point, so as to obtain the initial current , voltage and leakage current .

[0049] Current The true value fluctuates over time and at time point the current values are as follows (unit: A):

[0050] Voltage The true value fluctuates over time and at time point the voltage values are as follows (unit: V):

[0051] Leakage current The true value fluctuates over time and at time point the leakage current is as follows (unit: mA):

[0052] To simulate the noise and uncertainty in the actual situation, this embodiment introduces random fluctuations to perturb the true value of each data point. Current noise , voltage noise and leakage current noise follow a normal distribution. The standard deviations of current noise , voltage noise and leakage current noise are respectively: Current noise

[0053] Voltage noise

[0054] Leakage current noise

[0055] The true values obtained by adding noise are:

[0056]

[0057]

[0058] At time point the current noise , voltage noise and leakage current noise are -0.05 A, 0.5 V, 2.0 mA respectively. Then at moment, the true values of current, voltage and leakage current are:

[0059]

[0060]

[0061] Similarly, the noise at other time points can be randomly generated by a normal distribution, and finally a fault data set is obtained.

[0062] By repeating the above steps, the true values and noise values at all times are generated, and finally a complete fault data set is obtained. :

[0063] Fault data set contains data at time points, and each data point contains the true values of current, voltage, and leakage current.

[0064] Fault data set can be used for: Fault classification: According to the abnormal patterns of current, voltage, and leakage current, the fault types are classified into current faults, overvoltage / undervoltage, leakage, etc.

[0065] Fault simulation: Use these data to simulate various electrical faults that may occur in the low-voltage power distribution area, and combine with the control system for hardware-in-the-loop simulation.

[0066] Optimized operation and maintenance: Optimize the maintenance and fault detection of equipment based on this data set to help operation and maintenance personnel identify potential problems in advance and avoid system failures.

[0067] Example 4: This example further defines the specific content of classifying all fault data into a current fault data set, a current magnitude data set, and a leakage current data set on the basis of Example 1.

[0068] The current fault data set is:

[0069] Among them, is the current fault data set, is the fault threshold of the current, is the fault threshold of the leakage current; The current magnitude data set is:

[0070] Among them, is the current magnitude data set, is the minimum value of the normal current, is the maximum value of the normal current, is the minimum value of the normal voltage, is the maximum value of the normal voltage; The leakage current data set is:

[0071] Among them, is the leakage current data set, is the threshold value of the leakage current.

[0072] In this embodiment, by introducing the current fault data set , the current magnitude data set and the leakage current data set classification criteria, different types of faults can be more effectively identified and located from a large amount of data. The definitions of these data sets provide clear threshold values, making the screening and classification of fault data more accurate.

[0073] Current fault data set By setting the threshold values of the current and the leakage current, it is ensured that only the data with fault characteristics are extracted, avoiding the interference of noise or normal data. Current magnitude data set Can help confirm the situation of the current and voltage within the normal operating range, facilitating the judgment of whether there are abnormal fluctuations. Leakage current data set By introducing the leakage current threshold value, abnormal leakage current can be detected in a timely manner, preventing damage to the equipment and system caused by the leakage risk.

[0074] Embodiment 5: On the basis of Embodiment 1, this embodiment defines the specific parameters for selecting thyristors that meet the current requirements, selecting contactors that meet the current requirements, and selecting leakage current generators that meet the current requirements, as follows: The thyristor can withstand the maximum fault current is:

[0075] The conduction current of the thyristor after receiving the control signal is:

[0076] Among them, is the response curve of the thyristor, is the control signal of the thyristor, is the corresponding current value in the current fault data set.

[0077] The output current of the contactor after receiving the control signal is: is:

[0078] The current fluctuation range of the contactor is:

[0079] Among them, is the response function of the contactor, is the current value of the current magnitude data set.

[0080] After the leakage current generator receives the control signal the output current is:

[0081] The rated current of the leakage current generator is greater than or equal to the maximum leakage current in the leakage current data set:

[0082] Among them, is the function for dynamically adjusting the control signal of the leakage current generator according to the simulated leakage current magnitude, is the current value of the leakage current data set.

[0083] In this embodiment, by setting the maximum rated current requirements for each component (thyristor, contactor, and leakage current generator), it is ensured that the device will not operate overloaded during actual operation. The setting of these rated currents enables each component to withstand the maximum current value related to the fault, thus avoiding damage to the device due to overloaded operation.

[0084] The rated current of the thyristor can ensure that the thyristor can withstand the situation of the maximum current in the current fault data set and will not fail due to excessive fault current. The current fluctuation range of the contactor can ensure that the contactor can adapt to the maximum current fluctuation in the current magnitude data set, avoiding faults or untimely responses of the contactor under the action of the control signal.

[0085] The rated current of the leakage current generator can ensure that the leakage current generator can simulate the maximum leakage current in the leakage current data set, ensuring that the system can effectively simulate and respond to leakage current faults. This embodiment ensures the normal operation of the device under various fault conditions, prevents device damage caused by excessive current, and improves the reliability of the system.

[0086] Embodiment 5: When performing three-phase short-circuit simulation, the fault simulation controller controls the contactor control module to simultaneously close the contactors of the three-phase lines, directly short-circuiting the three-phase lines. By adjusting the thyristor control module, the magnitude and duration of the short-circuit current are precisely controlled. Through the preset fault current levels (500A, 400A, 300A, 200A, 100A), the fault simulation controller controls the thyristor control module and the contactor control module to select the corresponding contactor combination and thyristor conduction angle to achieve precise control of the fault current.

[0087] When performing three-phase short-circuit simulation, the fault simulation controller controls the contactor control module to perform contactor closing operations on any two-phase lines to achieve two-phase short-circuit fault simulation. Similarly, the short-circuit current is adjusted by controlling the thyristor control module. Through the preset fault current levels (500A, 400A, 300A, 200A, 100A), the fault simulation controller controls the thyristor control module and the contactor control module to select the corresponding contactor combination and thyristor conduction angle to achieve precise control of the fault current.

[0088] Embodiment 6: When performing single-phase grounding simulation, the selected phase line is connected to the grounding terminal through a contactor, and the contactor simulates the single-phase grounding fault through the contactor control module. The grounding resistance can be set as needed to simulate different grounding conditions.

[0089] Embodiment 7: This embodiment is provided with an overcurrent protection circuit. When the detected current exceeds the set threshold, the fault loop is automatically cut off to prevent equipment damage. An emergency stop button is provided in the fault simulation controller. Once an emergency occurs, all outputs can be immediately cut off to ensure the safety of personnel and equipment. This embodiment monitors the working status of each module and the output current in real time, and displays relevant information through indicator lights or a display screen to facilitate fault troubleshooting and maintenance.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A low voltage area semi-physical simulation modeling method, characterized in that: The following steps are involved: Obtain all fault data of the low voltage area and generate a fault data set; Classify all fault data into current fault data set, current magnitude data set and leakage current data set; According to the current fault data set, select the thyristor that meets the current requirements; According to the current size data set, select the contactor that meets the current requirements; According to the leakage current data set, a leakage current generator that meets the current requirements is selected; Thyristors, contactors and leakage current generators that meet the current requirements are selected and connected in parallel to the fault simulation controller to establish a semi-physical simulation model of the low-voltage substation. The fault simulation controller is used to control the size and duration of the thyristor simulated fault current, to control the contactor to simulate the on-off of the current, and to control the current generator to simulate three-phase leakage current or single-phase leakage current.

2. A low voltage area semi-physical simulation modeling method according to claim 1, characterized in that: The specific method of obtaining all fault data of the low voltage area and generating a fault data set is as follows: All fault data of the low voltage area including time series Fault data, where each fault data includes a data point In time Current at the moment ,Voltage and leakage current ; For current ,Voltage and leakage current Assign random fluctuations to obtain the true value of the current , voltage true value and the actual value of leakage current : in, is the current noise, is the voltage noise, is leakage current noise; According to the actual value of current , voltage true value and the actual value of leakage current , build a time series based The fault data set is obtained: in, is the total amount of fault data.

3. A low voltage area semi-physical simulation modeling method according to claim 2, characterized in that: The specific method of classifying all fault data into current fault data set, current magnitude data set and leakage current data set is as follows: The current fault data set is: in, is the current fault data set, is the fault threshold of the current, is the fault threshold of leakage current; The current magnitude data set is: in, is the current magnitude data set, is the minimum value of normal current, is the maximum value of normal current, is the minimum normal voltage. It is the maximum value of normal voltage; The leakage current data set is: in, is the leakage current data set, is the leakage current threshold.

4. A low voltage area semi-physical simulation modeling method according to claim 1, characterized in that: According to the current fault data set, when selecting a thyristor that meets the current requirements, the thyristor can withstand the maximum fault current for: The conduction current of the thyristor after receiving the control signal for: in, is the response curve of the thyristor, is the control signal of the thyristor, is the corresponding current value in the current fault data set.

5. A low voltage area semi-physical simulation modeling method according to claim 1, characterized in that: When a contactor that meets the current requirements is selected according to the current size data set, the contactor receives a control signal Output current after for: Current fluctuation range of contactor for: in, is the response function of the contactor, is the current value of the current magnitude dataset.

6. A low voltage area semi-physical simulation modeling method according to claim 1, characterized in that: When a leakage current generator that meets the current requirements is selected according to the leakage current data set, the leakage current generator receives a control signal Output current after for: The rated current of the leakage current generator is greater than or equal to the maximum leakage current in the leakage current data set: in, The control signal of the leakage current generator dynamically adjusts the function according to the simulated leakage current size. is the current value of the leakage current dataset.

7. A semi-physical simulation model of a low-voltage area, characterized in that: include: A fault simulation controller is used to receive control instructions, analyze the control instructions, and generate thyristor control signals, contactor control signals, and leakage current transmitter control signals; A thyristor control module, used for receiving a thyristor control signal and simulating the magnitude and duration of a fault current according to the thyristor control signal; A contactor control module is used to receive a contactor control signal and simulate the contactor to switch on and off with current according to the contactor control signal; The current transmitter is used for receiving the leakage current transmitter control signal and simulating the three-phase leakage current or the single-phase leakage current according to the leakage current transmitter control signal.

8. A low voltage area semi-physical simulation model according to claim 7, characterized in that: It includes wiring terminals for connecting with an external system, receiving data from the external system, and generating control instructions to send to a fault simulation controller.

9. A low voltage area semi-physical simulation model according to claim 7, characterized in that: The adjustment range of the current transmitter is 0~2.5A.

10. A low voltage area semi-physical simulation model according to claim 7, characterized in that: The fault current range of the thyristor control module is 500A, 400A, 300A, 200A and 100A.

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